1. Field of the Invention
This invention relates to means for delivering light to the blood supply of a human body to treat mood disorders and sleep and body cycle problems in humans. More particularly, the present invention concerns a portable and wearable light source apparatus, and methods related thereto, for delivering light to the blood supply by exposing a nonocular portion of the body to light in preselected wavelengths for preselected periods of time at optimal times of the day.
2. The Related Art
Seasonal affective disorder (SAD) is a form of recurrent depressive or bipolar disorder that seems to occur at times in the year when the natural amount of light decreases, such as in the winter. Symptoms of SAD include hypersomnia, carbohydrate-craving and weight gain, as well as panic disorders and other ailments. In such cases, it has been found to be effective to apply light therapy, that is, to introduce the body to artificial light of varying intensities and wavelengths and at different times of the day, in order to increase the amount of light provided to the body. See, e.g., “Winter Depression, and Phototherapy”, Gysin F.; Gross F. Acta Med Port (Portugal) December 1997, 10 (12) p 887–93.
Other types of non-seasonal, major depressive disorders, such as bulimia, have also been found to respond favorably to the application of various types of artificial light to supplement the natural light to the body of the subject. See, e.g., “Light Therapy in Bulimia Nervosa,” Blouin A. G. et al., Department of Psychiatry, Ottawa Civic Hospital, Ontario, Canada. Psychiatry Res (Ireland) Feb. 28, 1996, 60(1) p 1–9.
Humans have an intrinsic body clock that responds to light cues to aid in synchronizing activities to the rising and setting of the sun. This phenomenon is referred to as the circadian cycle or circadian clock and is known to control a variety of physiological processes, including daily fluctuations in body temperature, hormone production, and even sleep itself.
The circadian cycle may become disoriented or confused, so that sleep-related disorders develop. For example, a person traveling through various time zones often has difficulty acclimating the circadian cycle to a new time zone that may be hours different from the previous time zone. This problem is commonly referred to as “jet lag” and usually is resolved in a few days. Other sleep-related disorders may be more chronic and very difficult to cure or overcome.
In such sleep disorder cases, it has also been determined that light therapy can be quite effective in helping the circadian cycle to adapt. In particular, research has indicated that light can be provided not only to the retina but to extraocular portions of the body to create a circadian response. U.S. Pat. No. 6,135,117 (Campbell et al.) discloses methods for providing nonocular light to the body to treat circadian rhythm problems and various sleep disorders. Campbell indicates that the delivery of extraocular light stimulus to certain regions, such as the popliteal region, can mediate and shift the phase of a circadian cycle. U.S. Pat. No. 6,164,787 (Seki) discloses an apparatus positioned beneath an airplane seat for administering light to the popliteal region to affect the circadian cycle during extended flights.
In the Campbell et al. patent, light was delivered using large fiber-optic light pads designed to treat jaundice in newborns. These pads were attached to a bulky power supply. In the Seki patent, light was administered by fixed apparatus disposed beneath the airplane seat connected to a halogen lamp in a vented metal housing having a fan attached thereto. Neither system lends itself to portability.
Seasonal affective disorder (SAD) and other mood disorders, as well as circadian disorders and other sleep problems, require periodic timed treatment given at precise times over a period of several days or weeks. During and between treatment times, the subject needs to be free to move about and take care of normal activities. In particular, the treatment of circadian problems presupposes that the subject is treated before, during or after sleep and/or travel.
Accordingly, it is important that the treating device be easily portable and, optionally, wearable so that the subject is able to carry out normal activities during treatment. Moreover, the nature of the treatment requires that a power supply be included, which must also be portable and wearable. In addition, the time intervals and intensity of treatment may vary widely, depending on the subject and the type and severity of disorder. Accordingly, a portable control device may also be needed for effective treatment. A wearable unit may be useful for providing periodic treatment of varying times and intensities while not causing substantial discomfort or interfering with the mobility of the subject.
It has also been determined that some wavelengths of light are more effective in treating certain disorders than others. Thus, treatment using light with a single wavelength or a plurality of wavelengths within a fairly small range is often preferred. Accordingly, a means for light delivery is needed that can provide monochromatic light focused on the desired light wavelength or range of light wavelengths needed to treat a particular disorder.